Alarm tripping mechanism



Feb. 5, 1957 J, LA c v ZJSQEEQ ALARM TRIPPING MECHANISM Filed June 11,1954 QATTOR/VEYS United States Patent ALARM TRIPPHQG MECHANISM Frank 1.La Cavern, Cleveland, @hio Application June 11, 1954, Serial No. 436,057

11 Claims. (Cl. 200--61.93)

This invention relates to an a "um tripping mechanism for use inconnection with burglar alarms and particularly a tripping mechanism foruse in connection with electrically operated alarms such as described inmy copending application Serial No. l53,972, filed April 4, i950 and nowabandoned.

As pointed out in the above entitled application, it is desirable to proisle for use in connection with a single burglar alarm device a triggermechanism operated by a trip cord which, at locations remote from thetrigger mechanism and alarm device, can positioned across severalprobable paths of intruder into the premises to be guarded by the rl armdevice.

in connection with such alarms, the trigger mechanism should berelatively free from accidental operation but at the same time should beoperable very readily by movement or release of the trip cord. it shouldbe operable by the trip cord when the cord is engaged and moved slightlyby the intruder with pressure so light as to be unnoticea'ble to him.

The trigger mechanism should be such that the trip cord can be Withdrawnreadily as it is installed across the paths to be guarded yet, in eventthe trip cord is broken or released, it will not be tangled in any wayby rewinding or retraction by the trigger mechanism. For best effects,the trigger mechanism should operate quietly so that the intruder is notmade aware or" what has caused the alarm to operate.

Generally the mechanism alarm of the present invention is one which issimple, compact, and light, quiet in operation, and readily installablein operating condition in the place to be guarded thereby.

in general, the tripping mechanism comprises a platform member which issupported for movement, a switch operating device which is movable by aspring or gravity from an inoperative to a switch operating position,and a dead center member which is operatively connected to the platformso to constrai the switch operating device from movement to theoperative position so long as the dead center member is in lead centerposition and to release the switch operating device so that it canoperate the switch when the platform is moved suificiently to move thedead center member out of dead center position. The platfo so moved bymeans of a trip cord which pro. rably cited directly to it, though itmay be attached center member so that the platform member s moved bycord through the medium of the dead center in More specific featuresreside in the provision ol means for locking the switch operating devicein an inoperative position; of means for connecting the free end of thetrip cord so that it can become loosened readily by a force unnoticeabieby the intruder and not be broken by an intruder; and of means forreleasing cord so that it can be unreeled and located where desired andyet cannot be rewound by the tripping mechanism until the trippingmechanism is again reset for that express purpose.

Various other objects and advantages will become ap- 2 parent from thefollowing description wherein reference is made to the drawings, inwhich:

Figure l is a front elevation of the device embodying the principles ofthe present invention, part being in section;

Figure 2 is an enlarged fragmentary sectional view taken on the line Z-2of Figure 1 and showing the dead cent-:1 member thereof in dead centerposition;

Figure 3 is a fragmentary top plan View of part of the deviceillustrated in Figure 2;

Figure 4 is a View similar to Figure 2 but showing the dead centermember at its extreme dead center position; and,

Figure 5 is a wiring diagram showing one manner of connecting the deviceof the controls of an alarm device.

Referring to the drawings, which illustrate a preferred embodiment ofthe invention, the invention is shown as one which is enclosed in asuitable casing 1 provided with suitable supporting brackets 2 which arereceivable in suitable Wall sockets for supporting the device.

The operating e rents of the device comprises genorally a platform membe3, a switch operating device 4, and a dead center member 5 which isoperatively con nected to the platform member 3 and switch operatingdevice i so as to holc the switch operating device in preset conditionin which it is inoperable and to release the switch operating device topermit it to move to the switch operating position.

The dead center member 5 is so arranged with respect to the platformmember 3 that upon movement of the platform member, the dead centermember is moved out of dead center position whereupon it releases theswitch operating device for moving to the switch operating positiondirection. The movement of the platform member is in response to a pullon or release of a trip cord 6 which, in the form illustrated, is shownas connected directly to the platform member 3 instead of indirectly byway of the dead center member 5.

Referring more specifically to the main parts of the device asdescribed, the platform member may comprise one end of the self-windingreel '7 which is mounted for rotation about an upright axis in the formillustrated. Thus, the platform member 3 is movable in fixed relation tothe reel 7.

The trip cord d is wound on the roe "1. A return spring 3 is operativelyconnected to the reel in a manner such that the spring 8 is wound up asthe cord d is unreeled by pulling the cord endwise and can rotate to urnand wind up the cord when the of the cord is released.

The switch operating device comprises a suitable guided rod 9non-rotatively mounted in a collar on the casing l. for axialreciprocation. Carried on the rod 5 is a switch operating finger illadapted to engage and close switches, such as indicated at if; and 13,when the rod, along with the linger Ill, is moved a predetermineddistance from a fully upwardly withdrawn position to a lowered position.The rod 9 and finger ii are urged the switch closing direction towardthe plane of the platform 3 by any suitable means, such gravity or acompression spring spnng deter 1S. Lhfi collar is provided with 16 whichengages a suitable notch 17 T latching the seating device in an in'ope ndependently of the dead center device 5.

Operatively interposed bctwe... the device and the platform 3 is thedead center member 5 heretofore mentioned. The dead center mom er 5 isarranged so that one end engages the platform member 3 and prevents themovement of the device t to switch operating position. In the formillustrated, the dead center member is in the form of a pendulum havinga shank portion 1% and a foot portion 19. The pendulum is arranged forrocking in a vertical plane in the form illustrated. For this purposmit'Patented Feb. 5 1951 maybe mounted on a suitable laterally extending arm20 carried on the rod 9. It is mounted on the arm 20 for rockingmovement about a horizontal axis. Due to its weight and its distancefrom the pivotal axis of the dead center member 5, the foot 19 normallycauses the dead center member to assume a vertical position asillustrated in Figure 2. However, it may be that the alarm trippingmechanism as a whole may be tilted so that gravity cannot be dependedupon to hold the pendulum in the upright position. Accordingly, acentering spring 22 is provided and is connected to the casing l and tothe member 5 so as to normally yieldably hold the member 5 with its bodyportion 13 in a rocked position in which it is at right angles to theplane of the platform member 3. The foot 19 is preferably provided witha-fla'ttened bottom surface 23 which rests on the platform 3. Since thissurface 23 is somewhat elongated it tends to steady the dead centermember in position when it is-pressed against the platform member 3 andrequires a somewhat greater movement of the platform 3 in eitherdirection to move the member 5 out of dead center position. Theelongated bottom 25 thereby eliminates over-sensitivity of the deadcenter member and assists it in assuming the proper position whensetting the mechanism.

The rod is such that its inner end, indicated at 24, is spaced from theplatform member 3 when the dead center member 5 is in operating positionwith its bottom surface 23 hearing against the platform 3. This spacedrelation is such that when the rod 9 is released by the dead'centermember 5, the rod can be moved a sufiicient distance by the spring toclose the switches 12 and 13 and preferably approach quite closely tothe plane of the platform 3. The rod Q is provided with an elongatedaxially extend ing notch in which the detent 16 is operable, the lengthof the notch 25 being such, and its ends being so located, as to limitthe outward movement of the rod 9 axially and cause the finger 11 to bepositioned just clear of the switches 12 and 13 and to lift the deadcenter member 5 clear of the patform 3. The location of the oppositeends of the notch 25 is such to engage the detent 16 and arrest inwardmovement of the reel in a position in which the finger 11 has closed theswitches 12 and 13 and the inner end 24 of the rod is clear of theplatform member 3.

On the platform member 3 are a plurality of circumferentially spacedstops 26, these preferably being tongues turned out of the sheet metalforming the upper end of the reel. These stops preferably are spaced 180apart about the reel axis and extend above the platform member 3 asufficient distance so that when the rod 9 is in its innermost position,as indicated by the dotted lines in Figure 1, one or the other of thestops 26, depending upon the direction of rotation of the reel, willengage the rod and arrest rotation of the reel after a maximum of a halfturn in either direction after the mechanism has been tripped.

The free outer end of the cord 6 is provided with a ball 27 by which thecord 6 may be detachably secured to a suitable anchor. Preferably, theanchor is such as indicated at 28 and is adapted to be fastened to awall or some structure remote from the mechanism. The anchor 28preferably comprises a plurality of resilient fingers 29 which grip theball and hold it against removal by the pressure of the return springbutpermit its detachment by a pull exerted on the cord 6 materiallygreater than that exerted by the return spring 8.

When the rod 9 is released by a movement of the p1atform member 3 whichdisposes thedead center member 5 out of dead center position, it ismoved downwardly by the spring 15 so that the switches 12 and 13 areclosed successively. The closure of these switches may complete acircuit to the device described in my copending applica tion or to thesuitable alarm mechanism. For example, as shown in Figure 5, the switch12 may be connected to a suitable alarm bell .B and to an outlet box 0which has terminals 0 and b which may be connected to the input leadwires of the device in my said copending application.

The switch 13 may be connected to a suitable plug-in receptacle intowhich the usual plug for a cord leading to alarm lights can be connectedfor connecting the lights to the 110 volt circuit. A circuit leading tothe switch 13 is provided with the usual plug P by which it can beconnected to the 110 volt line.

For convenience the self-winding reel may be of the type provided withthe usual spring Winding drum 30 so that the spring can be wound to thedesired tension. Any spring retur reel provided with the conventionalwind-up means nding up the reel may be provided, as the details thereofform no part of the present invention.

In operation, it is assumed that the circuit is connected as illustratedin'Figure 5. A suitable electric cord leading to alarm lights, ifdesired by the owner of the premises, are plugged into the receptacle R.The alarm device of my copending application may be connected to theterminals a and [1. These connections are made while the rod 9 is heldin the upper or retracted position by engagement of the detent 3.6 inthe notch 1'7. The device is fastened on a wall by the brackets 2. Inthis condition, the reel 7 is freely rotatable except for the resistingforce of the spring 8. The anchor 23 is installed in the desiredlocation about the premises.

Next, the trip cord is pulled and unreeled by the gripping the leadingend and leading it through suitable wall supported hooks or eyes, ifnecessary, across the selected paths about the premises. When the cordis unwound and extended in its desired position, the ball 27 on the freeend is snapped between the fingers 29 so that the free end of the cord 6is held in fixed but readily detachable position against the force ofthe return spring 3 of the reel '7.

With the cord thus positioned, the rod 9 is pressed inwardly of thecasing i, releasing the detent 16 from the notch 17 and disposing it inthe notch 25. The rod 9 moves downwardly under the force of the spring15 until the undersurface or bottom 23 of the foot 19 of the dead centermember 5 rests squarely on the platform member 3 wihch, in the formillustrated, is the upper end of the reel 7. In this position, thefinger 1.1 is positioned just above the operating position with respectto the switches 12 and 13 and the lower inner end of the rod 9 is clearof the upper end of the reel and of the stops 26.

These relative positions of the operating parts are re tained until thedead center member 5 is moved out of its dead center position. if anytension is exerted on the cord 6, the reel is rotated in one direction,thus disposing the dead center member 5 to one side of dead center. Onthe other hand, if the cord 5 becomes detached the spring 8 rotates thereel in the opposite direction, thus disposing the dead center member 5at the opposite side of dead center. In either event, when the member 5passes beyond the dead center limit, the rod 9 is released and thefinger 11 closes the switches 32 and 13 to initiate operation of thealarms controlled thereby.

It is apparent, therefore, that the device is operated effectively whenany intruder strikes the cord and exerts a slight amount of pressurethereagainst or causes it to break or become released from the anchor28. Also, in the event of failure of the cord 6 or accidental detachmentof it from one of the eyelets or from the anchor 28, the device willfail safe in that it thereby becomes operative and initiates the alarmoperation. As a result of making the device operative either by tensionon the cord 6 or release of tension, the owner of the premises cannot bemisled into belief that the alarm which he has set is ready foroperation when, in fact, the cord has become dislodged or broken.

When the rod 9 has become released there ordinarily would be a tendencyfor the spring 8 to wind up the reel rapidly and thus cause the treeendof the cord 6 to whip about and possibly become entangled. However, dueto the engagement of the stops 26 with the rod 9, rotation of the reelmore than a half revolution is prevented. The

same is true should the intruders foot become entangled in the cord andtend to unroll an unnecessary amount of it.

By using a cord 6 which is non-metallic readily combustible material themechanism may he used as a fire alarm. Thus if the cord is burned intwo, the spring 8 will immediately actuate the reel so as to trip themechanism.

It is apparent from the foregoing description that I have provided asimple, light, compact, and efficient tripping mechanism for thepurposes described and one that fails safe in event of inadvertentbreakage or release of its trip cord.

Further, I have provided a mechanism which does not require anyexternally exposed power conductors for initiating the closing of theswitches.

Having thus described my invention, I claim:

1. An alarm tripping mechanism comprising a platform member, meanssupporting the platform member for movement along a predetermined path,a switch operating device movable from an inoperative position to anoperative position, means urging the device toward operative position, aswitch operatively connected to said device operated thereby when thedevice is moved to its operative position, a dead center member havingone end operatively connected to the device and its other endoperatively connected to the platform member for movement of the deadcenter member by the platform member out of dead center position whenthe platform member is moved a predetermined distance along said path,said dead center member constraining the device from movement toward itsoperative position while the dead center member is in its dead centerposition and releasing the device for movement to its operative positionwhen the dead center member is moved out of its dead center position,and a trip cord connected to the platform member and operable when movedendwise under tension to move the platform member along saidpredetermined path a predetermined distance.

2. An alarm tripping mechanism according to claim 1 characterized inthat said platform member is rotatable about a predetermined axis, andsaid dead center member is a compression member and is rockable into andout of dead center positions by frictional movement of its said otherend in the direction of rotation of the platform member.

3. An alarm tripping mechanism according to claim 2 characterized inthat a reel is provided, said cord is wound on said reel, and saidplatform member is rotatable in fixed relan'on to the reel.

4. An alarm tripping mechanism according to claim 3 characterized inthat one end of the reel is the platform member.

5. An alarm tripping mechanism according to claim 3 characterized inthat self-winding spring means are connected to the reel for rotatingthe reel in a direction for winding the cord on the reel.

6. An alarm tripping mechanism according to claim 5 characterized inthat stop means are provided and are movable in fixed relation to thereel, cooperable stop means are provided in fixed relation to the switchoperating device and are disposed in the path of the stop means of thereel when the device is in switch closing position for stopping themovement of the reel by the spring means after a limited movement of thereel by the spring means.

7. An alarm tripping mechanism according to claim 6 characterized inthat a ball is connected to the cord, a detachable grip adapted to beconnected to a supporting member is provided and comprises spacedresilient fingers adapted to receive the ball therebetween and yieldablyretain the ball in position against the return force of the spring meansand to release the ball when a pull is exerted on the cord appreciablygreater than the pull exerted by the spring means.

8. An alarm tripping mechanism comprising a platform member, meanssupporting the platform member for rotation, a switch operating devicemovable, and normally urged, from an inoperative to an operativeposition, a switch operatively connected to said device for operationthereby when the device moves to said operative position, a rigid deadcenter member interposed between the device and platform member and, atone end, resting against the platform member when the dead center memberis in a dead center position so as to constrain the device from movementto the switch operating position while the dead center member is in saiddead center position and to release the device for movement to switchoperating position when the dead center member is moved out of a deadcenter position, said dead center member being operatively connected tothe platform member for movement out of dead center position by rotationof the platform member a predetermined distance, a reel rotatable infixed relation to the platform member, and a trip cord connected to thereel and operable when moved endwise under tension to rotate the reel.

9. A trigger mechanism for a burglar alarm comprising a self-windingreel, means supporting the reel for rotation about a predetermined axis,a trip cord Wound on the reel, a switch operating device movable towardone end of the reel and arranged when moved a predetermined distancetoward said end of the reel to operate a switch, means urging the devicetoward the end of the reel, a compression dead center member operativelyinterposed between the device and said one end of the reel and normallyconstraining said device from movement toward the reel to switchoperating position and being displaceable from dead center position soas to release the device for movement to switch operating position uponrotation of the reel in either direction a predetermined distance from agiven position.

10. A trigger mechanism for a burglar alarm according to claim 9characterized in that the dead center device is a pendulum pivotallymounted on the switch operating device and depending from its pivotalconnection for swinging in opposite directions along the path ofrotation of the end of the reel about an axis parallel to the plane ofthe end of the reel.

11. A trigger mechanism for a burglar alarm according to claim 10characterized in that means are provided to latch said switch operatingdevice in an inoperative position with the pendulum spaced out ofcontact with the end of the reel.

References Cited in the file of this patent UNITED STATES PATENTS1,238,532 Lemberg Aug. 28, 1917 1,240,896 Spielman Sept. 25, 19172,014,474 Hopkins Sept. 17, 1935

